The all-India rainfall surplus has returned to double digits (10 per cent) midway into August under the benign watch of a monsoon depression that managed to retain strength into the evening on Tuesday, beyond the weatherman’s expectations. India Meteorological Department (IMD) expects it to weaken into a well-marked low-pressure area early into Wednesday morning, which will extend the heavy rain spell over Rajasthan, Gujarat and West Madhya Pradesh.

The 24 hours ending Tuesday morning saw extremely heavy rains lash parts of East Gujarat while it was heavy to very heavy over East Rajasthan and Madhya Pradesh and heavy rainfall over Jammu, Konkan, Goa, Madhya Maharashtra, Saurashtra, Kutch, Chhattisgarh, West Rajasthan and Himachal Pradesh as also to the eastern parts of the country including Rayalaseema, Vidarbha, and the hills of West Bengal.

Third ‘low’ in the making

Meanwhile, the IMD also confirmed that the third in the current string of low-pressure areas will form over the North Bay of Bengal by Friday. Considering that the system will originate in the North Bay, and given the IMD forecast that the western end of the all-important monsoon trough may start shifting to the North towards its normal position, it is likely that the ‘low’ may move slightly northward of its predecessors’ track and bring rain into the moisture-stressed areas of Bihar, West Bengal, Jharkhand, Uttar Pradesh from the weekend. Jharkhand and West Bengal have witnessed some improvement in recent days.

Deficit in Uttar Pradesh

As on Tuesday, the meteorological subdivision of East Uttar Pradesh bore the heaviest deficit at 47 per cent, while West Uttar Pradesh and Bihar followed with an identical 40 per cent. Jharkhand (-36 per cent) and the plains of West Bengal (-35 per cent) realised the narrowest of gains as the current depression hovered over the region in the initial days. The situation may undergo further improvement after the incoming ‘low’ kicks in from the weekend.

It will trigger fairly widespread to widespread light to moderate rainfall over the plains of West Bengal, Odisha, Jharkhand, Chhattisgarh and East Madhya Pradesh from Thursday to Saturday. Isolated heavy to very heavy rainfall is likely over Odisha on Friday and Saturday. Isolated heavy rainfall is predicted over Chhattisgarh and the plains of West Bengal on Friday and over Bihar and East Madhya Pradesh on Saturday.

Widespread rain forecast

Fairly widespread to widespread light to moderate rainfall with isolated heavy falls and thunderstorm and lightning are likely over Himachal Pradesh on Friday and Saturday and Uttarakhand from Thursday to Saturday; and over East Uttar Pradesh on Friday and Saturday and West Uttar Pradesh on Saturday. The projected movement of the rain belt along this region indicates the northward-than-usual movement of the rain-driving low-pressure area along a path set up by an obliging monsoon trough. Interaction with an incoming western disturbance might scale up the rain along the hills.

By Tuesday evening, the heaviest of the rain clouds set up by the prevailing depression over East Rajasthan had drifted away to the northern parts of Gujarat and beyond the international border into South Pakistan. On the Indian side, these clouds hung over Gandhidham, Charanka and Khavda in North Gujarat; and less intense over Mahesana and Palanpur in Gujarat; Bhinwal, Udaipur, Bhilwara, and Dungarpur in Rajasthan and over adjoining West Madhya Pradesh.

Clouds over East Bay

Fresh clouds had formed also over East and South-East Bay of Bengal on Tuesday evening, extending from the Andaman and Nicobar Islands before blooming as heavy and intense clouds over most parts of Myanmar as the winds converged in advance of formation of the new low-pressure area. Model projections indicate the parent cyclonic circulation may form over Myanmar before it steps out into the Bay and grow into a full-fledged ‘low’ over the next three days.